Re: Rebuilding an OBIT

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "R.E.Burnett by way of Terry Fritz <twftesla-at-uswest-dot-net>" <R.E.Burnett-at-newcastle.ac.uk>


Hi Sue, and all,

TRANSFORMERS DO NOT SATURATE DUE TO TOO MUCH CURRENT BEING DRAWN !

The ammount of current you can draw from the secondary is limited by the
resistance of the windings and the coupling between primary and
secondary.  If you draw too much current you will simply overheat the
windings.  Therefore current rating is determined from the acceptable
temperature rise during operation.

Transformer cores saturate if you apply too much voltage for a given
number of primary turns.  (This causes excessive primary current to be
drawn from the mains.)

The core is actually nearest to saturation when the transformer is running
off load.  As you draw more current from the secondary,  the
secondary field starts to cancel that generated by the primary.  As the
load is increased the core actually moves further away from saturation !

I hope this helps to clear up this subject of transformer saturation,
which seems to come up quite often.
						Cheers,

						-Richie,

> I have a 10KV, 23mA OBIT that burned out in furnace duty last Winter. I
> finally got around to depotting it and found that the only part of the
> secondary that was any good is the bobbin. I am in the process of rewinding
> it with 34 AWG wire (much thicker than what was on there before!). I am
> [snip]
> My question is: How much current can I get out of this thing before the core
> saturates and gives me grief. A lot of folks have written about knocking
> shunts out of NSTs, but has any one else ever tinkered with OBIT cores?
> 
> Thanks,
> Sue
> 
> 
> 
>